This invention relates to vehicle monitoring systems, and particularly to alert and warning systems for monitoring the location of the vehicle on a transportation route having a plurality of stops from a location proximate to a designated stop on the route.
Transportation systems such as municipal and school bus systems have for years operated according to schedules of stop locations and times which are either conveyed individually to intended passengers or published for the general public. Since buses often depart from their schedules, bus riders depending only on bus schedules must adjust their own schedules to allow for early or late arrival of their bus. These schedule adjustments not only increase the effective riding time for any bus rider, but they increase an individual's exposure to inclement weather and, in some localities, to the risk of harassment or harm from other individuals. School buses, particularly those involved in transportation of handicapped students, sometimes wait for late arriving students. This not only wastes fuel but directly increases the riding time for all the riders on the bus.
An early warning system devised by Fruchey et al., described in U.S. Pat. No. 4,297,672, includes a radio transmitting system on a bus and a plurality of receiving systems in proximity to individual predesignated pickup regions. The transmitter on the bus broadcasts an RF signal sequentially modulated by a plurality of audio frequencies generated by individual tone generators. Each receiver has a corresponding plurality of tunable tone decoders, and any receiver which is set to respond to the particular multi-tone sequential signal being broadcast provides an audible and visual alarm upon receipt of that signal. This system can provide early warning only to passengers to be picked up by a bus at the immediately upcoming stop. In some situations, such as where stops are located close to each other, advance notice of only one stop does not give a passenger sufficient time to travel to the bus stop to meet the arriving bus. This system is also inconvenient for the bus driver, who must operate a plurality of tone selector switches at each stop to set the particular ordered combination of audio frequencies to uniquely identify the immediately upcoming stop.
In a radio signaling system for monitoring transportation vehicles, it is sometimes necessary to change route or stop designations to accommodate changing transportation conditions. It would be advantageous in such cases to be able to change desired parameters without requiring the involvement of the owner of any individual receiver. This would eliminate inconvenience to private individuals such as parents of school children who ride a school bus in the system, and minimize the inconvenience of the system operator in reprogramming receivers.